SOUTH SAN FRANCISCO — Dr. Donald Francis gets his greatest satisfaction from prevention.

“Never do you feel like you accomplish something as much as you do with preventive medicine,” said Francis, a physician who played a critical role in eradicating smallpox when he worked with the Centers for Disease Control and Prevention.

He’s now executive director of Global Solutions for Infectious Diseases, a South San Francisco firm funded largely by the Bill and Melinda Gates Foundation that’s hard at work developing vaccines to stop the spread of diseases that kill millions worldwide each year.

Francis spoke Thursday here at a one-day event organized by BayBio, a biotechnology industry trade association. He shared the stage during a noontime panel discussion with Dr. Thomas Brewer, senior program officer for infectious diseases in the Gates Foundation’s Global Health Program. The theme of the event was “Doing Well by Doing Right.”

The two doctors described to an audience of several hundred how the world’s attention is turning, at last, to ending the misery and death from diseases in scores of countries with far fewer resources than the United States, thanks in large part to initiatives from the Gates Foundation.

“It’s a revolutionary time, really,” Francis said. He described the Gates Foundation’s focus on developing drugs for infectious diseases that rarely, if ever, appear in the United States, but kill and maim millions worldwide.

According to the World Health Organization, tuberculosis killed 1.6 million in 2005, while malaria takes the lives of than one million annually, mostly infants and young children. An estimated 50 million worldwide develop dengue fever annually, killing up to 5 percent of them. Diarrhea illnesses kill up to three million children annually, and many other infectious and parasitic diseases add to the toll.

Francis’ firm is working on developing vaccines for dengue and HIV, and other companies are developing treatments for malaria, tuberculosis, and diarrhea illnesses, among other diseases.

The Gates Foundation, which has a nearly $39 billion endowment, states its guiding principle is “every life has equal value,” and funds drug development for treating or preventing diseases usually not typically pursued by large pharmaceutical firms.

Francis described how partnerships between foundations and pharmaceutical firms may create successful and novel business models that encourage other companies to develop drugs that save lives in developing countries. The low profit margins on these products, coupled with high development and distribution costs, deter most companies from entering these markets, he said.

Francis sympathized with these concerns, but said new ways of looking at profit margins could help companies tap into new markets.

Most pharmaceutical firms look for “blockbuster” drugs with high profit margins, often focused on chronic diseases like heart disease or osteoporosis. But with a vaccine for malaria, for example, “earning pennies per dose” can pay off when selling millions of vials, Francis said.

“It’s a different kind of marketing,” he said.

In Europe, there’s far greater interest from governments and citizens in supporting drug and vaccine development for infectious diseases and parasites that typically afflict populations in poorer countries, such as those in Africa, parts of Asia and around the equator.

In contrast, in the United States, there’s far more focus on treating chronic conditions often linked with lifestyles, rather than infectious diseases.

affecting millions in faraway lands, particularly since vaccines have eliminated the most fearsome plagues in America, such as smallpox and polio.

“In America, we’re kind of an isolated place,” Francis said. But more Americans are traveling, he said, increasing their exposure to exotic bugs. “You can’t isolate diseases with that kind of travel,” he emphasized.

Brewer, with the Gates Foundation, also described a world “getting flatter” with globalization, and Francis pointed out that healthy populations do better economically, and economically strong countries are more politically stable.

In an interview after the panel discussion, Francis pondered the cost of disease, using the example of polio, which he still spends several weeks a year trying to eradicate in Northern India — one of its last strongholds.

“Instead of your costs going to disease, it’s going to the economy,” he said. “You can imagine what a case of polio costs in the long term.”

But the U.S. mind-set has a ways to go in recognizing the worth of prevention, and not just state-of-the-art treatments for chronic diseases, Francis said.

“People love to put their money into the National Institutes of Health,” he commented, which typically funds basic research.

“But we’re not mature enough to value preventative medicine,” Francis added, pointing to financially strapped public health agencies in most U.S. jurisdictions.

Otto Warmbier was arrested in January 2016 at the end of a brief tourist visit to North Korea. He had been medically evacuated and was being treated at the University of Cincinnati Medical Center when he died at age 22.